Correcting lenses utilized in the manufacture of fluorescent screen of color picture tubes

Abstract

The correcting lens comprises a plurality of regions which are formed at at least one portion of the effective surfaces on both sides of the lens by means of a plurality of border lines which are discontinuous in only one direction. The regions on one side are inclined in a direction different from that of the regions on the opposite side of the lens.

What is claimed is: 
     
       1. A correcting lens of an exposure device utilized to form a fluorescent screen of a colour picture tube, the correcting lens having effective surfaces on opposite sides thereof, each effective surface comprising a plurality of regions divided by a plurality of border lines and each having a specified refractive characteristic to exposure light, said border lines on the respective sides dividing one effective surface of the correcting lens in a direction different from another direction in which the opposite effective surface of the correcting lens is divided, and being discontinuous in only one direction the regions on said opposite sides being inclined in substantially different directions to provide said specified refractive characteristic such that the exposure light path through the correcting lens approximates the ultimate electron beam locus by cooperation of the regions on one side of the correcting lens with those on the opposite side thereof. 
     
     
       2. The correcting lens according to claim 1 wherein the respective border lines on both sides are substantially parallel with each other. 
     
     
       3. The correcting lens according to claim 1 wherein the surfaces of respective regions formed on both sides of the lens are flat. 
     
     
       4. The correcting lens according to claim 1 wherein the surfaces of respective regions formed on both sides of the lens are curved. 
     
     
       5. The lens as defined in claim 4, wherein said elements of said first effective surface are perpendicular to said elements of said second effective surface. 
     
     
       6. The correcting lens according to claim 1 wherein said regions on one side are inclined substantially in the same direction. 
     
     
       7. The correcting lens according to claim 1 wherein the discontinuous border lines defining the regions on one side intersect the discontinuous border lines defining the regions on the other side of the lens at substantially right angles. 
     
     
       8. The correcting lens according to claim 1 wherein said regions on at least one side of the lens are inclined in at least two different directions. 
     
     
       9. A correcting lens for use in the formation of a colour picture tube screen including, a first effective surface comprising a plurality of parallel strip-shaped elements separated by boundaries of discontinuity, each of said elements separately contoured to reduce misregister in said tube, and   a second effective surface opposite said first effective surface, said second effective surface comprising a plurality of elements separated by boundaries of discontinuity, each of said elements of said second effective surface separately contoured to additionally reduce misregister in said tube.   
     
     
       10. The lens as defined in claim 9, wherein said second effective surface comprises strip-shaped elements, each of said elements being parallel to each other.